From treehouses to soapbox racers, father-son projects make for great childhood memories. But Brad Pitt and his sons had a slightly more unusual hobby: creating a zombie-proof hideout!

“Maddox and Pax became obsessed with zombies after seeing Brad act on the set of World War Z, in which his character battles the undead,” divulges a family friend. “So Brad thought it’d be a great project to make a ‘safe house’ in their French chateau in case of zombie attacks.”

The family bunker – outfitted with a water-purification system and non-perishable food – was such a success, they’re planning more projects! “They want to zombie-proof their Los Angeles mansion next!”